
Shader "Unity Shader Book/Chapter6/Specular Vertex Level"{
    Properties{
        _Diffuse("Diffuse", Color) = (1, 1, 1, 1)
        _Specular("Specular", Color) = (1, 1, 1, 1)
        _Gloss("Gloss", Range(8.0, 256)) = 20
    }
    
    SubShader{
        Pass{
            Tags{"LightMode" = "ForwardBase"}
            
            CGPROGRAM

            #pragma vertex vert
            #pragma fragment frag
            #include "Lighting.cginc"

            fixed4 _Diffuse;
            fixed4 _Specular;
            float _Gloss;

            struct a2v
            {
                float4 vertex: POSITION;
                float3 normal: NORMAL;
            };

            struct v2f
            {
                float4 pos: SV_POSITION;
                float3 worldNormal: NORMAL;
                float3 worldPos: TEXCOORD0;
            };

            v2f vert(a2v v)
            {
                v2f o;

                o.pos = UnityObjectToClipPos(v.vertex);

                o.worldPos = mul(unity_ObjectToWorld, v.vertex).xyz;

                o.worldNormal = mul(v.normal, unity_WorldToObject);

                return o;
            }

            fixed4 frag(v2f i): SV_Target
            {
                fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.rgb;

                fixed3 worldNormal = normalize(i.worldNormal);
                fixed3 worldLightDir = normalize(_WorldSpaceLightPos0.xyz);
                fixed3 diffuse = _LightColor0.rgb * _Diffuse.rgb * saturate(dot(worldNormal, worldLightDir));

                fixed3 reflectDir = normalize(reflect(-worldLightDir, worldNormal));
                fixed3 viewDir = normalize(_WorldSpaceCameraPos.xyz - i.worldPos.xyz);
                fixed3 specular = _LightColor0.rgb * _Specular.rgb * pow(saturate(dot(reflectDir, viewDir)), _Gloss);
                
                return fixed4(ambient + diffuse + specular, 1.0);
            }

            ENDCG
        }    
    }
}